Interstate 93 will be narrowed in each direction on most weekends this summer as part of a $98 million state highway construction project to replace 14 deteriorated bridges in Medford.
Work already is underway to prepare the eight-lane highway for the first bridge replacement project in Medford in at least 50 years. Work includes regrading the median strip, with most work to be done overnight and on weekends. Seven spans, which elevate the highway above local roads, are located on each side of the highway.
I-93 is heavily traveled, with traffic counts in 2007 totaling almost 685,000 daily, according to the most recent data available from the state Department of Transportation. The constant rumble and vibration of cars, trucks, and other vehicles has weakened the spans. Emergency repairs were required last August after large potholes opened up on a stretch of the road near Valley Street.
“These are very old bridges, and there are [signs] of advanced deterioration,’’ said Peter C. Rapp of J.F. White Contracting Co. of Framingham, lead contractor for the project, during a hearing April 14 in Medford City Hall.
Subcontractors include
Each bridge will be demolished and replaced with precast concrete panels. Work is scheduled to begin the weekend of June 3, at Riverside Avenue. It will continue for 10 straight weekends, state officials said, with the only except the July Fourth weekend. To minimize traffic delays and detours, work will be done over a 55-hour period, starting each Friday at 10 p.m. and ending each Monday before 5 a.m., according to the state Department of Transportation.
Sound barriers also will be installed on I-93 southbound. The panels, which aim to shield residents from highway traffic, are now 75 percent designed. Installation will not begin until fall, officials said.
The Medford project has been dubbed the “Fast 14’’ because of the rapid-fire pace of construction. Each bridge is scheduled to be replaced in a single weekend. If the project were done lane by lane, construction would take four to five years, Rapp said.
“We are going to use the best technology available to accelerate the actual construction work,’’ he added.
On weekdays, all eight lanes of the highway will be open. And despite weekend lane closings, traffic will still move in each direction. When work is being done on one side of the highway, the opposite side will be split in half, with two lanes heading south and two heading north. A trial run is scheduled for Friday, according to the state.
Digital message boards will be displayed on surrounding highways, such as Route 128 and Interstate 495, to alert motorists to detours and estimated travel times. “We will be able to give real-time information in advance so they [motorists] can make a decision’’ about which route to travel, said Erik R. Maki, a senior project manager at Tetra Tech.
Motorists may also sign up for text alerts and e-mails and will be able to view detour maps and a construction schedule at www.93fast14.com, which has been set up by the transportation department. Motorists will also be able to tun into 700-AM on their radios for updates.
Maki said the traffic plan calls for the Fellsway and Route 60 to be used as detours.
Project managers said they are confident in their traffic management plan.
Kathy McCabe can be reached at kmccabe@globe.com. 
